Cleft lip repair (cheiloplasty) is surgical procedure to correct a groove-like defect in the lip.
A cleft lip does not join together (fuse) properly during embryonic development. Surgical repair corrects the defect, preventing future problems with breathing, speaking, and eating, and improving the person’s physical appearance.
Cleft lip is the second most common embryonic (congenital) deformity. (Club foot is the most common congenital deformity.) Cleft lip occurs in approximately one in 750–1,000 live births. The highest incidence exists in North American Indians and Japanese (approximately one in 350 births). African Americans and Africans represent the lowest incidence of cleft lip deformity (approximately one in 1,500 births). There is a higher frequency of clefting in certain populations of Scandinavia and Middle European countries.
Cleft lip occurs more commonly in males, while cleft palate is more likely to occur in females. Cleft lip alone (without cleft palate) occurs in approximately 20% of cases across both genders. The majority of cases—80%—have both cleft lip and cleft palate. A unilateral cleft lip, commonly occurring on the left side, is more common than a bilateral cleft lip.
Most cases of cleft lip have no known cause. However, there is a strong genetic correlation. Other single gene defects that are associated with cleft lip include: Van der Woude syndrome, Opitz Syndrome, Aarskog syndrome, Fryns syndrome, Waardenburg syndrome, and Coffin-Siris syndrome. Approximately 5% of cleft conditions are associated with a genetic syndrome. Most of these syndromes do not include mental retardation.
Facial cleft has been implicated with maternal exposure to environmental causes, such as rubella or medications that can harm the developing embryo. These medications include steroids, antiseizure drugs, vitamin A, and oral anti-acne medications (such as Acutane) taken during the first three months of pregnancy. Cleft lip is also associated with fetal alcohol syndrome and maternal diabetes.
Risk of cleft lip increases with paternal age, especially over 30 years at the time of conception. Generally, the risk is higher when both parents are over 30 years of age. However, most cases seem to be isolated within the family with no obvious causation.
When the affected child has unilateral cleft lip and palate, the risk for subsequent children increases to 4.2%. Advances in high resolution ultrasonography (prenatal ultrasound exam) have made it possible to detect facial abnormalities in the developing embryo (in utero).
Important structures of the embryo’s mouth form at four to seven weeks of gestation. Development during this period entails migration and fusion of mesenchymal cells with facial structures. If this migration and fusion is interrupted (usually by a combination of genetic and environmental factors), a cleft can develop along the lip. The type of clefting varies with the embryonic stage when its development occurred.
There are several types of cleft lip, ranging from a small groove on the border of the upper lip to a larger deformity that extends into the floor of the nostril and part of the maxilla (upper jawbone).
Unilateral cleft lip results from failure of the maxillary prominence on the affected side to fuse with medial nasal prominences. The result is called a persistant labial groove. The cells of the lip become stretched and the tissues in the persistent groove break down, resulting in a lip that is divided into medial (middle) and lateral (side) portions. In some cases, a bridge of tissue (simart band) joins together the two incomplete lip portions.
Bilateral cleft lip occurs in a fashion similar to the unilateral cleft. Patients with bilateral cleft lip may have varying degrees of deformity on each side of the defect. An anatomical structure (intermaxillary segment) projects to the front and hangs unattached. Defects associated with bilateral cleft lip are particularly problematic due to discontinuity of the muscle fibers of the orbicularis oris (primary muscle of the lip.) This deformity can result in closure of the mouth and pursing of the lip.
In addition to classification as unilateral or bilateral, cleft lips are further classified as complete or incomplete. A complete cleft involves the entire lip, and typically the alveolar arch. An incomplete cleft involves only part of the lip. The Iowa system (which also classifies cleft palate) classifies cleft lip in five groups:
- Group I—clefts of the lip only
- Group II—clefts of palate only
- Group III—clefts of lip, alveolus, and palate
- Group IV—clefts of lip and alveolus
- Group V—miscellaneous
Another widely accepted cleft lip classification is based on recommendations of the American Cleft Palate Association. This classification divides cleft lip into unilateral or bilateral (right, left or extent) in thirds—(i.e., one-third, two-thirds, three-thirds), or median cleft lip, the extent of which is also measured in thirds.